The objectives of this protocol are to determine the maximum tolerated dose of Mitomycin C (MMC) when given in combination with CPT-11, to determine if the pharmacokinetic behavior of CPT-11 is altered prior to administration of MMC, to determine the effect of CPT-11 and MMC on the expression of DT-Diaphorase and the Topo I gene, and to evaluate the antitumor activity of the combination.